DES GRANDS BARRAGES
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VINGT TROISIÈME CONGRÈS
DES GRANDS BARRAGES
Brasilia, May 2009
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ENVIRONMENTAL INFLUENCE TO THE PROJECT DESIGN,A STUDY CASE ON ASAHAN NO. 3 HYDROPOWER PROJECT – INDONESIA(*)
MAS’UD MARSAM
Chief of Oversight Committee JB-I, PT PLN (Persero)
INDONESIA
ABSTRACT
The environmental and social matters is now becoming more sensitive issues, such as housing resettlement, land acquisition, compensation pricings and the other social matters. Most of the Financial Institution put the good environmental handling as their loan requirement in order to be sure that the project implementation would not harm the society. The project evaluation must consider this matters in it’s Feasibility Study.
The environmental aspect is not just considered from the construction viewpoint but also the problems that might happenthroughout the operation period. The experiences showed that effort spent to overcome the problem was tremendous both financial and time. In some cases the environmental costs might so big that put the project become not feasible anymore.
The land acquisition for the reservoir is one of the most problem in development of a Hydropower Plant in Indonesia, because the required area is huge and the land is commonly fertile. The people in this area usually are farmers and the agricultural land is the only livelihood they have. The resettled people should be assured that they will get the better or at least similar life condition compare to their previous.
In 1988, the Asahan No. 3 Hydropower Plant was originally designed as a Peak Power Plant of 400 MWinstalled capacity. Due to the financial and other reasons, up to now the project is not yet implemented. Recent change of the people’s way of thinking in natural environment had forced the developer to modify the project design to become a run-off river type Power Plant, eliminated the big reservoir and the inhabitants resettlement.
1.INTRODUCTION
Geogaphically, Indonesia is located between the Indian and Pacific ocean. The climate is wet tropical, influences by west and east monsoon wind. The west wind blows in the months of November to May brings rain to the area. The rest of the moths is dry period which is less rain, except for several mountainouspart.and consists of many islands.
The total area of the archipelago is about 5.2 million square kilometers and of it,1.9 sq kms is land, while the rest is sea.Most of the big islands are mountainuous with quite intense of rain, creates plentiful potential sites for hydropower plants. One of the huge site is Mamberamo of Papua, who has about 8000 MW potential. But, since its location is very remote and no surrounding consumers of that scale, the development of this power is not realized yet.
The Hydropower Potential Study (HPPS) had been conducted by PT PLN (Persero) a State-own Company (PLN) who is responsible for public Electricity Generation and Distribution on 1983showed that the total potentials of Indonesia was 75000 MW. The review of this study on 1999recommends to develop more than 26000 MW from the sites that has over than 10 MW potential capacity. More than 15300 MW was recommended to be implemented until 2018,considering the demand growth and generation mix required by the Electricity System in each island.
The growth of the national electricity demand in Indonesia for the last 8 years is 8 % per year in average. Actually this figure is not a real one, since the are still many are queuing and listed in the waiting list for new connection that could not be realized by PLN because limitation of the power capasity. The development of the new Plants were very small, because the government’s financial condition was still suffering from the impact of the monetary crisis in 1998. This situation led to the electricity crisis in all Indonesia’s regions, especially in the outside Java and Bali. The government then initiated to develop 10000 MW Coal Power Plant to end up thecrisis. The plants are distributed in the Java-Bali System for 6900 MW and the rest are spreaded in the outside Java islands.
North Sumatra, the region that will be discussed in this paper is part of the Sumatra Electricity Sytem, connected to the Central Sumatra by 150 kV Transmission Line in the east part of the region. The peak load of this sub-system is 1183MW on September 2008, while the nett capacity is 1338 MW.It shows that the nett reserve margin of the plant is only 12%. This figure is too small for an Electricity System that needs at least 30% nett reserve margin for secure operation. PLN is now constructing the new plants of 542 MW capacity in North Sumatra, consists of 230 MW Coal Steam Power Plant, 302 Diesel and Gas Turbine Plants (fast track program) and 10 MW Geothermal Plant of Independent Power Producer (IPP) that will in full operation in the beginning of 2009. This additional capacity will increase power availability and reserve margin will become 35% in this region.
The newly developed power plants, except the Geothermals are oil fuel consumption type. The new composition of the plants’ energy production in North Sumatraaccording to it’s fuel use will be : (1) oil fuel base = 92.7%, (2) Geothermal = 0.5%, Hydropower = 6.8%. From this figure, it can be noticed that the energy production cost of this region is mainly affected by oil price. In the last year when the oil price increased very much, this region becoming one of the most expensive energy production cost of PLN. Based on this fact, the development of new hydropower plant is most recommendable.
Based on the HPPS review on 1998, the recommended Hydropower potential sites in North Sumatraregion are 22 locations with total capacity about 906.3MW. The development of this potentials will reduce the dependability on fuel oil in producing energy. This green energy will make the most use of the natural resource for public benefit and also will contribute in reducing the pollution caused by the fuel oil plants. Further detail study is required to implement this type of plant.
The Asahan No 3 Hydro Power Plant (HPP), one of the prospectivehydropower project in the AsahanRiver scheme was firstly identified in the Overall Hydropower Development Plan of Lake Toba and AsahanRiver Basins in 1972. The Feasibility Report was prepared in 1982, financially supported by Japan International Cooperation Agency (JICA). In the Detailed Design work conducted in 1987, Asahan No 3 was intended for peaker plant with reservoir and 4 x 100 MW installed capacity.
The recommendation to execute the project had been addressed several time, but no implementation so far up to now. The region also is suffering of limitation of electric supply even before Asahan No 3 was investigated. There were many reasons for this implementation delay, such as who will be the executing agency of this project, the environment and social issues, and the project financing. Considering that reasons, PLN is seeking the otherconsept that significantly reduce the project cost, environment and social impacts.
- ASAHANRIVER HYDROPOWER SCHEME
The origin of Asahan river is LakeToba in North Sumatra, a lake created from huge volcano eruption with surface area of 11000 sq km. The lake become a very big storage of water for hydropower plants who are operated along Asahan river. The Asahan river is the only outlet of the lake and runs north-east direction downhill to the sea. In the upper part, the river streams through a hilly area with quite deep gorge and some waterfalls, then it flows gently through lowland area to the sea of Malacca Strait.
In the Asahan river scheme, at least there are 5 sites for hydropower development, which are the Asahan No 2 (2 sites) that are already in operation and The Asahan No 1 which is under constructionandscheduled to be completed in 2010. Schematic cascade sytem is shown in figure 1 and table 1. The no 2 plants were in function since 1984, serving an Aluminium Smelting factory of PT. Inalum without substantial interruption. The real hydrological data provided from these plants is the precise information for further development in the river scheme.
Fig. 1
AsahanRiver Scheme
Table 1
AsahanRiverScheme, Hydropower Potential Sites
No / Name / Capacity (MW) / Status / Remarks1 / Asahan 1 / 2 x 90 / Under construction / Scheduled 2010 in operation by Independent Power Producer (IPP)
2 / Asahan 2
a / Siguragura HEPP / 4 x 71.5 / In operation / Completed on 1983 by
PT. Inalum
b / Tangga HEPP / 4 x 79.3 / In operation / Completed on 1984 by
PT. Inalum
3 / Asahan 3 / (4 x 100)
2 x 77 / Construction preparation / Detailed design on 1987
Review Design on 2004 by PLN
4 / Asahan 4 / 90 / Site identification / Study on April 1972 by PLN
Total Capacity / 1024.2
The Asahan No 4 HPP was originally designed to re-regulate water discharge after Asahan No 3 operation by peaker plant of 4 x 400 MW concept to avoid flood in the downstream area during maximum operation of this plant. Due to recent design modification of No 3, the No 4 plant have to be reviewed again from the operational and financial view.
Further downside development might be possible, but it might financially less benefit because the project will be rather costly since the gorges have already flat with low water head.
- ASAHAN NO 3 HYDROPOWER PLANT DESIGN
3.1.DESIGN CONCEPT
In the beginning, the Asahan No 3 HPP was designed to be a peaker plant in the North Sumatra Electricity Subsystem to fill the power requirement during the peak time, which take place during 05.00 to 10.00 pm. During past time the peak load could be doubled of it’s daytime, characterized mostly by residences uses. Recently, the electricity consumption curve in this area had changed, driven by the development of the industry in the last 2 decades. The average daily typical load of this sub-sytem in 2007/2008 is illustrated in figure 2. It shows that the daily load is not so fluctuated along the day. In the peak time the system load increases by 200 MW, or only about 25% of the daytime.
Fig. 2
Daily Typical Load of North Sumatra Sub-system2007/2008
As seen in the figure, more than 80% of energy was produced by oil fuel. The oil price boosting in the last years increased rapidly the average energy production cost in this sub-system. In this constrain and in compliance with the Government’s energy policy to use most of the renewable energy, development of Asahan No 3 HPP is highly recommended.The recent typical load curve shows that the base plant is required to fill the power demand, while the peak plant, even needed, the capacity is reduced significantly.
3.2.THE ORIGINAL DESIGN
As mentioned in the former section, the original concept of the Asahan No 3 HPP was for peaker plant. This purpose can be achieved by creating an adequatewater reservoir by constructing a Centre Core Rockfill Dam in the Asahan valley. The reservoir gross capacity was 90 x 106 m3 and of that, the active capacity was 11 x 106 m3. The optimal examination of the development scale,resulted 4 x 100 MW installed capacity with 1930 GWh annual energy production. The detailed design was completed on 1987 by PLN.
To get the maximum output, the storage should be discharged by 247.4 m3/second for 5 hours of operation. Out of that time the output power will be depended to the water availability and the electricity system requirement. The peak discharge will flood the downstream area, since the firm discharge was only 137.9 m3/second. We experienced when the surface of LakeToba was coming to Flood Water Level of 905.00 m in 1984, the water was discharged by 250 m3/second for some days and flood happened in the downstream lowland area. To avoid this adversity effect, an afterbay dam in the downstream of the Asahan No 3 Power House should be considered. In this facility, a Power Plant can be installed, harnessing the available water head and discharge. The capacity of the plant have to be studied separately.
Total land use for project area, consists of access road, office, base camps, plant’s structure and material operational activities are 2500 ha. The 275 kV Transmission Lines to evacuate the Power runs 245 km long double circuits to Galang and Binjai Substations. It also needs to relocate 14 existing towers of the 275 kV Transmission Line of PT. Inalum and a 3 km long public road.
The reservoir surface area will be 2.4 km2 and willsubmerge village of Tangga. The number of 97 household of 447 family members (data of January 2008) that have to be resettled. Almost of thempossess paddy field and the productive houseyards. The resettle location is in the area downward to the area of Bandar Pulau district. The latest findings at 1995 indicated that the residents wanted to move to Tangga II in Sabungan village with 5 km long from the Tangga I their original village. The new village is not yet developed and needs an access road of 3 kms from the main road.
The construction of rockfill dam of 129 m high needs an embankment of 9,200,000 m3 rock and filler materials. The concrete structures also requires a lot of aggregate materials which will be obtain from the quarry sites at the right bank side downstream of the dam. The area of this quarry mainly consists of local plantation such as coffee. The impermeable core materials are obtained from borrow areas in the inundated area and in the downstream side of the dam.
The waterway consist of a concrete lined headrace tunnel, circular section with diameter 9.2 m and 5,750.3 m long and steel lined penstocks, 2 lines in the inclined section with diameter from 6 to 5.6 m and 4 lines in the downstream with diameter from 3.9 to 3.15 m. The gross head is 192.3 m, while the net head is 183.6 m. The Power House is located in the open area, accommodates 4 x 100 MW installed capacity Hydro Generating Plant.
The public perception to the project were relatively good at that time and they hope to get profit from the construction activities. Most of them also accepted the compensation by money than resettle to the new location. They hope to have a better condition after the project implementation, such as social facilities, improvement of infrastructures and so on.
The society mainly dominated by the Batak ethnic groups who are very strong in traditional ‘adat’ (ritual). The resettlement process would be a very special ceremony. Also the relocation of the family grave should be by ‘adat’ ritual that might quite costly. All of the offer and decision to the group have to beresolved by the ‘adat’leader.
The construction cost of this scheme is estimated at USD 866 million in 1987. The implementation of the Project was scheduled to be second to Asahan No 1 (see Asahan River Hydropower Scheme above), because the No 1 is cheaper and no need to construct a Dam. The existed Regulating Dam of Asahan No 2 will become the Intake Dam of the Asahan No 1 HPP.
When PLN decided to carry on design review of Asahan No 3 HPP, it passed more than 15 years already from the finalization of detailed design without any sign of project implementation. Amongst the reasons are decision for the executing agency of this project, financial availability and economy crisis on 1998 that the country is still sufferingof. On the other side, North Sumatra region is still experiencing lack of power supply caused by the high electricity demand growth and inadequate development of new plants to cope with that demand.
3.3.DESIGN REVIEW OF ASAHAN NO 3 HPP
The power demand of North Sumatra region continue to growing and the waiting list for new connection keeps on increasing, forced PLN to formulate a solution for that. The fast track construction of 302 MW generating plants (‘fast track program’) is implemented, consist of 135 MW oil fuel Diesel Plants and 167 MW oil fuel Gas Turbine. Eventhough this immediate solution might dealt with the demand, the consequence to PLN is the energy production cost become very expensive.
The total non oil fuel plant capacity in this region is about 150 MW with less than 10% of total energy production of the region. Even before ‘fast track program’ was implemented, share of non oil fuel based energy was less than 10%. The ‘fast track’ actually increases the energy production cost in this area. The liable solution for this problem is maximum utilization of the natural resources in North Sumatra, i.e Geothermal and Hydropower.
As explained in the former paragraph, the recommended hydropower potentials in the region is about 900 MW, includes the Asahan No 3 HPP. Since the detailed design of this HPP was completed and the production of the existed plants, i.e the Asahan No 2 HPP is also already proofed, PLN initiated to do review design of the Asahan No 3 based on updated hydrological data to get the cheaper construction cost and minimize the environmental impact to surroundings.
In the Hydropower development, both natural and social environments often raises the problems that might lasts for years to solve. Unlike the developer who commonly places thismatter as important as the financial evaluation, the recent insight of the communities practically put this environment issue in the first consideration. The Environmental Impact Analysis (EIA) have to be conducted very carefully, because it relates to the sensitive issues of the communities.
The Kotapanjang HPP which is already in operation since 1999 is one example of the case. The Government and PLN were summoned before the court by the resettled people who were not satisfied to the resettlement program at that time. Some reasons were argued, such as the unfair compensation and the worsened of life after resettled. In Japan, the OECF (former name JBIC) and the Consultant were also summoned before the court and the process is still running in Tokyo.